In situ tailoring of material properties in 3D printed electronics

Abstract

Systems and methods for highly reproducible and focused plasma jet printing and patterning of materials using appropriate ink containing aerosol through nozzles with narrow orifice and tubes with controlled dielectric constant connected to high voltage power supply, in the presence of electric field and plasma, that enables morphological and/or bulk chemical modification and/or surface chemical modification of the material in the aerosol and/or the substrate prior to printing, during printing and post printing.

The invention claimed is: 
     
       1. An apparatus for printing crystalline metal surface comprising: a ink input in the form of aerosol from a solution containing one or more metal ion with an oxidation state of 1+ or more;
 a gas supply line for one or more gas; 
 an inner tube and an outer tube, in which the inner and outer tubes are made of dielectric material, and are of equal length, said inner tube terminating at an inner tapered nozzle, said outer tube terminating at an outer tapered nozzle, and in which a plasma discharge is generated and sustained in both said inner tube and said outer tube; 
 the inner tube carrying aerosolized metal ion and the outer tube carrying said one or more gasses; 
 one or more metal electrodes disposed along the circumference of the inner tube and connected to a high voltage power supply configured to generate said plasma discharge in both said inner tube and said outer tube; 
 wherein the plasma discharge is configured to reduce the oxidation state of the metal ion in aerosolized ink to elemental metal and direct the reduced metal towards the substrate in a dry form resulting in printing of conducting crystalline metal surface on a substrate. 
 
     
     
       2. An apparatus according to  claim 1 , wherein the gas comprises a non-reactive gas, a reactive gas, or a combination thereof. 
     
     
       3. An apparatus as recited in  claim 2 , wherein the gas comprises a non-reactive gas selected from a group consisting of helium, neon, argon, krypton, and xenon and/or reactive gas selected from a group consisting of hydrogen, nitrogen, acetylene, methane, ammonia, and a combination thereof. 
     
     
       4. An apparatus as recited in  claim 1 , wherein the inner and outer tubes of the print head nozzle has same or different thickness. 
     
     
       5. An apparatus as recited in  claim 2 , wherein the reactive and non reactive gases can be used i) prior to deposition ii) during deposition and iii) post deposition to create plasma discharge for tailoring material properties. 
     
     
       6. An apparatus as recited in  claim 1 , wherein one or more gas, dielectric constant and thickness of the inner and outer tubes, and distribution of electrodes can be appropriately chosen to get high momentum transfer to the material and also used to get highly directional jet to print materials with specific geometries, patterns and properties on 2 dimensional as well as 3 dimensional features. 
     
     
       7. An apparatus as recited in  claim 1 , wherein the metal comprises a transition metal. 
     
     
       8. An apparatus as recited in  claim 1 , wherein said gases used to generate the plasma and create a reducing environment are selected from the group consisting of helium, argon, hydrogen, nitrogen, or any hydrogen-containing reducing compounds. 
     
     
       9. An apparatus as recited in  claim 1 , wherein said gas used to generate the plasma is made to flow at a rate of from 10 sccm to 5000 sccm. 
     
     
       10. An apparatus as recited in  claim 1 , wherein the plasma is generated at atmospheric pressure and the temperature on the substrate falls in a range of 35 deg C. to 200 deg C. 
     
     
       11. An apparatus as recited in  claim 1 , wherein the three-dimensional conducting structure of metal is printed and grown with specific geometries in two and three dimensions. 
     
     
       12. An apparatus as recited in  claim 1 , further comprising printing and post treating the printed material to further reduce the oxidation state of the material and form crystalline structure. 
     
     
       13. A method of printing crystalline metal on a substrate, the method comprising:
 (a) introducing a material comprising metal ion with a oxidation state of 1+ or more into said inner dielectric tube of said apparatus of  claim 1 ; 
 (b) exposing said material comprising metal ion to atmospheric pressure plasma generated by said electrodes of said apparatus of  claim 1 , thereby reducing the oxidation state of the material to form elemental metal; 
 (c) directing the reduced elemental metal towards a substrate to print conducting crystalline metal onto said substrate. 
 
     
     
       14. The method of  claim 13 , wherein said plasma can be treated on printed metal to further change the morphology, oxidation state, chemical bonding, spin state, crystallographic structure, strain, thickness, or a combination thereof. 
     
     
       15. The method of  claim 13 , wherein the said metal upon printing on the surface is crystalline and conducting in nature.